1. Field of the Invention
The present invention relates to a profile grinding machine for grinding a recess made open in the side face of a work, smoothly.
2. Related Art
Conventionally, in case a ground face inclined with respect to a vertical line is formed in the inner face of a recess made open in the side face of a work, as shown in FIG. 2, the work is fixed on a work table, and the grinding stone is manually inclined before the grinding operation in accordance with the angle of inclination of the ground face to be formed, so that the moving direction of the leading end of the grinding stone is set in parallel with the ground face to be formed. In case the angles of inclination of the ground faces to be formed are different for the individual faces, therefore, the angles of the grinding stone have to be readjusted for the individual faces thereby to complicate the profile grinding operations. Thus, there has been proposed (as referred to JP-A-10-138112, for example) a profile grinding machine, in which a movable base is so disposed on the back of the work table for supporting and fixing the work as can rock forward and backward, and rightward and leftward with respect to the work table, in which the movable base is provided with a first rocking frame having a first rocking action device automatically adjusted to rock forward and backward with respect to a first rocking shaft, and a second rocking frame disposed on the front side of the first rocking frame and having a second rocking action device automatically adjusted to rock rightward and leftward with respect to a second rocking shaft intersecting at a right angle with the first rocking shaft, and in which a grinding stone head having a stone wheel rotationally driven is so disposed on the front side of the second rocking frame as can reciprocate upward and downward.
In case, however, the profile grinding machine described in JP-A-10-138112 is used to grind the individual inner faces of the recess thereby to form the inclined ground faces, the grinding stone is inclined in advance to the angle of inclination of the ground faces. Therefore, the depth of cut of the work by the grinding stone is set constant from the cutting side of the grinding stone to the leaving side. In case, therefore, the grinding operation to start the cutting of the grinding stone from the upper face side of the work and to extract the grinding stone from the back face side of the work is performed from one side to the other of the recess in a top plan view, as shown in FIG. 7 and FIG. 8, there arises a problem that the grounding quantities of the lower face side (or the leaving side of a grinding stone 85), as indicated by broken lines, of a work 84 are excessive for the designed quantity in a corner area 83, in which two adjoining surfaces (or inner faces) 80 and 81 (or the surfaces 81 and 87) of a recess 82 of the work 84. This raises a limit to the precision in the inner face shape of the recess 82 after ground.
In case, moreover, the grinding operation is started from one side to the other of the recess 82, it is so performed with the leading end portion 86 of the grinding stone 85 being inclined with respect to the surfaces 80, 81 and 87 of the work 84 as to prevent the interference between the grinding stone 85 and one side of the work 84 and the excessive wear of the leading end portion 86 of the grinding stone 85. As a result, when the leading end portion 86 of the grinding stone 85 approaches the other side of the recess 82, there arise a problem that the side portion of the grinding stone 85 interferes with the other side of the recess 82 so that the grinding operation cannot be performed. This makes it necessary to turn a stone head 88 thereby to change the angle of inclination of the leading end portion 86 of the grinding stone 85 with respect to the surface 87 of the work 84. As shown in FIG. 8A, however, the position of the center axis of turn 89 of the stone head 88 and the center position of the leading end portion 86 of the grinding stone 85 are generally spaced by a distance L. As shown in FIG. 8B, therefore, when the stone head 88 is turned, the center of the leading end portion 86 moves on the center axis of turn 89 along the arc having a radius of a distance L between the center axis of turn 89 and the center of the leading end portion 86 of the grinding stone 85. As a result, there arises a problem that the grinding stone 85 collides against the other side of the recess 82, as shown in FIG. 8C. Before the grinding stone 85 interferes with the other side of the recess 82, therefore, the grinding stone 85 is relieved from the work 84 so that the angle of inclination of the leading end portion 86 of the grinding stone 85 with respect to the surface of the work 84 is readjusted to reopen the grinding operation. Alternatively, the grinding operations of the inner faces of the recess 82 are individually performed by dividing them for one side area and the other side area. As a result, the preparing steps before the grinding operations increase to raise a problem that the total time period required for the grinding operations is elongated.